Nanostructure of metaphosphate glasses

Glassy metaphosphates of one, two, and three valence metals were studied by Rayleigh and Mandel'shtam-Brilllouin scattering (RMBS) spectroscopy and high temperature ultrasonic (HTUS) measurements in glass melts. Ratios of Rayleigh scattering intensities to the Mandel'shtam-Brilllouin scattering ones (Landau-Placzek ratios) were measured. Results are discussed in terms of density, concentration, and anisotropy fluctuations "freezing" when the melt is being cooled to solid glass state. Combined application of RMBS and HTUS made it possible to independently estimate the contributions of "frozen-in" density and concentration fluctuations into Rayleigh scattering. It was found that in most cases about half Rayleigh scattering intensity is caused by chemical nanoinhomogeneities of a glass, that is the "frozen-in" concentration fluctuations. Comparison of RMBS, HTUS and small angle X ray scattering (SAXS) data led to the conclusion that NaPO3 and Ba(PO3)(2) glasses were characterized by the highest chemical homogeneity on nanometer scale.